1. Field
The embodiment of the present invention relates to an organic light emitting display device and a driving method thereof.
2. Description of Related Art
In recent years, various flat panel display devices with reduced weight and volume in comparison to a cathode ray tube have been developed. Examples of the flat panel display devices include a liquid crystal display device, a field emission display device, a plasma display panel, and an organic light emitting display device.
An organic light emitting display device displays images by using organic light emitting diodes that emit light by recombination of electrons and holes. Such an organic light emitting display device has a rapid response speed and is driven with low power consumption.
An organic light emitting display device includes a plurality of pixels that are arranged in a matrix at crossing regions of a plurality of data lines, scan lines, and power lines. Each pixel typically includes an organic light emitting diode, two or more transistors including a driving transistor, and one or more capacitors.
A disadvantage of such an organic light emitting display device is that the amount of current that flows to the organic light emitting diode varies depending on a threshold voltage of the driving transistor provided in each of the pixels. Characteristics of the driving transistor provided in each of the pixels vary due to inconsistencies of a manufacturing process of the driving transistor. It is difficult to manufacture the transistors used in each of the pixels in the organic light emitting display device to have the same characteristics given the current processing technology. This results in variability in the threshold voltage of the driving transistors in each of the pixels, which causes a non-uniform display luminance.
A compensation circuit including a plurality of transistors and capacitors in each of the pixels is added to the organic light emitting display device. The compensation circuit included in each of the pixels charges a voltage corresponding to a threshold voltage of the driving transistor to thereby compensate for the variability in threshold voltages among the driving transistors in each of the pixels.
A driving method using a frequency of 120 Hz or more has been required in order to remove a motion blur phenomenon. However, in the case of high-speed driving at 120 Hz or more, a charging duration of the threshold voltage of the driving transistor is shortened, such that compensation of the threshold voltage of the driving transistor may become impossible.